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MONITORING,2.0 GROUNDWATER SAMPLING AND ANALYSIS On May 3 2011, to monitor the plume of impacted groundwater and to comply with groundwater monitoring ring requirements, g n it nm nt l monitored and sampled the eight site wells, On July 1, 2009, EHD directed that the site wells be monitored and sampled on a semi-annual basis according to Stag Water Resources Control Board (SWRCB) Resolution No. 2009-0142, dated May 19, 2009. Monitoring wd11s MW-7 and MW-8 continue to be sampled on an annual basis, during the first half of the year, according to EHD directive dated December , 200& 2.1 Groundwater it in To calculate the groundwater gradient and flow direction, Ramage Environmental measured the depth-to-groundwater in the eight monitoring wells to within 0.01-foot rising a water level indicator: The depth to the groundwater table in the wells ranged from 32.25 feet bgs in MW-6 to 36.00 feat bgs in MW-4. The rrr po ding groundwater surface elevations in the eight monitoring wells ranged from a high of 11.20 teat below mean sea level trnal in well MW-7 to a low of 12.02 feet below rn l'at -4. The resulting groundwater surface appears as an irregular plane generally dipping toward the northeast at a gradient of approximately 0.0021 foot/foot. groundwater surface contour snap is included as Figure 3„ and the well construction details, wellhead elevations and groundwater monitoring data are summarized in Table 5. 2.2 Groundwater lin lysis Following groundwater lural measurements, Ramage Environmental purged and sampled the eight walls. The wells were purged with a pump and dedicated disposable tubing until at least three well'casing volumes had been removed and/or after groundwater temperature, ply and electrical conductivity values had stabilized. Groundwater was sampled from the walls using disposable polyethylene bailers and laboratory-supplied containers. The sample containers were transported in an iced cooler<with chain-of-custody documentation to E ool h rn Environmental Labs E l ha r , a state of California certified hazardous waste testing laboratory (#2119). The sample information field sheets are included in Appendix Excelchern analyzed each groundwater sample for T PH-as-diesel and T P -as-jet fuel by EPA Method 801 , ` H- s-gasolin , benzene, toluene, t ylb rr ane; xylenes (BTEX) by EPA Method 8021B/8015M, and methyl tertiary butyl ether , di-isopropyl ether 1PE), ethyl tertiary butyl ether(ETBE), tertiary arnyl methyl ether(TAME), tertiary butanol (TBA), and 1,2- dichl ethan „2- b EPA Method 8260B.